[molpro-user] Linear dependent basis

[John Keith]

Hi all,

I'm trying to run single reference ab initio calculations on
transition metal complexes and build up enough calculations to
extrapolate to the CBS limit.

My molecule is the PdCl4 dianion, and I'm using the Stuttgart Pd
pseudopotential and the (aug)-cc-pvNZ basis sets on all other valence
electrons. All are taken from the EMSL basis set library. I get SCF
convergence with cc-pvDZ, aug-cc-pvDZ, cc-pvTZ, and aug-cc-pvTZ basis
sets, but at cc-pvQZ I run into an error saying:

------------------------
 Eigenvalues of metric

         1 0.212E-08 0.406E-05 0.681E-05 0.681E-05 0.835E-05 0.102E-04
0.103E-04 0.106E-04

 ERROR: BASIS LINEARLY DEPENDENT OR WRONG S

 The current threshold for the smallest tolerated eigenvalue of S is   1.0D-08
------------------------

I spent some time searching the user-list and google, and I couldn't
find a solution I needed.  What I gather is that since my geometries
are reasonable, the jobs run fine with smaller basis sets, and since I
only have one eigenvalue below the threshold, this error probably just
comes from the fact my QZ basis is (not surprisingly) linearly
dependent and should be scaled down one or a few basis functions.

Pardon the naive question, but does someone know the "right" way to
modify this basis set so it is not linearly dependent, but that it is
also of desired quality for a meaningful CBS extrapolation? Is it as
straightforward as starting at the QZ basis and removing individual
diffuse functions until the basis set is not linearly dependent, or is
there a higher art to it?

My input file is:
***Pd_4Cl

cartesian

geomtyp=xyz
orient,mass
geometry={
5
Pd_4Cl calc
Pd   -0.213992    0.027380   -0.117721
Cl   -1.943705   -1.515957    0.437439
Cl    1.304488   -1.784426   -0.423439
Cl    1.515859    1.570547   -0.672946
Cl   -1.732472    1.839247    0.188003
}
set,charge=-2

<BASIS>

hf

In my <BASIS> block, I've been using a script to pasting the explicit
basis sets from the EMSL website into the input file. I don't want to
paste all those messy numbers here unless that's actually requested.

Thanks in advance!

--john

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Ph D. John A. Keith
Institut für Elektrochemie     Email: john.keith at uni-ulm.de
Universität Ulm                    Telephone: +49-731-50-26061
Albert-Einstein-Allee 47       URL: http://www.wag.caltech.edu/home/johnk
Ulm D-89069                       URL:
http://www.uni-ulm.de/theo_echem/index.shtml
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There is as much difference between us and ourselves as between us and others.

-Michel de Montaigne, essayist (1533-1592)
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